TROPICAL STORM RAFAEL SPECIAL DISCUSSION NUMBER   1
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL172012
730 PM AST FRI OCT 12 2012

A COMBINATION OF SATELLITE AND AIR FORCE RESERVE HURRICANE HUNTER
AIRCRAFT DATA SHOWS THAT THE LOW PRESSURE SYSTEM IN THE EASTERN
CARIBBEAN SEA HAS FORMED A CLOSED CIRCULATION...ALBEIT ONE WITH A
LARGE AREA OF LIGHT AND VARIABLE WINDS NEAR THE CENTER.
THEREFORE...THE SYSTEM NOW MEETS THE CRITERIA TO BE CONSIDERED A
TROPICAL CYCLONE. THE AIRCRAFT REPORTED 1500-FT FLIGHT-LEVEL WINDS
OF 43 KT AND SMFR WINDS OF 35 KT NEAR ST. VINCENT...AND BASED ON
THESE DATA THE SYSTEM IS UPGRADED TO TROPICAL STORM RAFAEL.  MOST OF
THE DEEP CONVECTION IS DISPLACED WELL EAST AND SOUTHEAST OF THE
CENTER DUE TO ABOUT 20 KT OF SOUTHWESTERLY SHEAR ON THE EAST SIDE
OF AN UPPER-LEVEL LOW CENTERED SOUTHWEST OF PUERTO RICO. THE SHIPS
MODEL SHOWS THE SHEAR PERSISTING FOR THE NEXT DAY OR SO BEFORE
RELAXING A BIT AS THE UPPER-LOW SHEARS OUT AND LIFTS NORTHWARD.
ONLY SLOW STRENGTHENING IS EXPECTED DURING THE FORECAST PERIOD.
SUBSEQUENTLY...AS THE SHEAR FROM THE UPPER LOW DECREASES...THE
CYCLONE BECOMES EMBEDDED IN STRONG SOUTHWESTERLY FLOW AHEAD OF A
LONGWAVE TROUGH AMPLIFYING OFF THE U.S. EAST COAST. THE OFFICIAL
NHC FORECAST IS CLOSEST TO THE SHIPS MODEL GUIDANCE THROUGH THE
PERIOD.

GIVEN THE RECENT FORMATION OF THE CENTER...THE INITIAL MOTION
ESTIMATE IS A VE